Lampholder



J. M. PISTEY LAMPHOLDER Feb. 25, 1964 Filed DEC. 51, T962 INVENTOR. .J5/f2? M P75 Z7@ BY um@ United States Patent O 3,l22,dtl LAMPHLDER .lohn M. Pistey, Fairfield, Conn., assigner to General Electric Company, a corporation of New York Filed Dee. 3l, i952, Ser. No. 243,627 lo Claims. (ill. 339-52) The present invention relates to lampholders for doubleended electric discharge lamps, such as iluorescent lamps, and in particular to fluorescent lampholders employing a movable plunger type or" contact positioning member.

Prior art iiuorescent larnps have commonly been supported and suitably energized by means of a pair of lampliolders, one of which includes a retractable or compressible plunger for positioning the contacts thereof. Such a lampholder is commonly referred to as a compressible lampholder. To enable the contact elements of these prior art compressible lampholders to eliciently interengage their mating contacts in associated fluorescent lamps, it has been considered both important and desirable for the lampholder contact elements to exert a biasing force upon the seated lamp contacts in a direction transverse to the axis of movement oi the plunger. Such a transverse biasing torce imparted by the lampholder contact element to its associated lamp contact, assures an effective wiping action between the contacts.

In the past it has been a widespread practice to construct compressible lampholders of the nature referred to, with one or more springs ior biasing separate and distinct contact elements and the plunger itself into the desired positions in the lampholder. The costs of these prior art lampholders have reilected a considerable expense due to labor and material costs which result from the use of the several parts and the shop operations required in assembling the lampholder. It has, therefore, been found desirable to provide an improved fluorescent lampholder which is simple in construction, relatively easy to assemble, and of substantially reduced overall cost, while at the smne time providing an elective contact wiping action.

Accordingly, it is a primary object of my invention to provide an improved fluorescent lampholder which is very ecient in operation and due to its relative simplicity can be manufactured at a reduced cost.

Another object of my invention is to provide an improved fluorescent lampholder wherein a compressible contact positioning plunger is utilized, and novel contact elements are included which bias the plunger into its operating position and also eiiect an eicient Contact wiping action upon interengagement with cooperating lamp contacts.

A further object of my invention is to provide an improved liuorescent lampholder which is compact and very reliable in operation.

In carrying out my invention, in one form thereof, I have provided a lampholder for receiving the contacts of a double contact fluorescent lamp. The lampholder includes an insulating housing, and a contact positioning plunger arranged in the housing for reciprocating movement relative thereto. The plunger has a transverse wall recessed from its outer end to provide an outwardly facing cavity for receivinT a lamp base. A central projection is formed within this cavity. This central projection has a pair of grooves formed on its opposite sides. ln

"ice

.2. my improved arrangement, a pair of contact making springs are arranged in spaced apart and insulated relationship within the lampholder housing. Each of these springs includes a irst resilient section disposed at one of its ends and a second resilient section comprising the remainder thereof. The rst resilient sections of the springs are extended through openings formed in the transverse Wall so that they terminate within the outwardly facing cavity. The second resilient sections are arranged in compression between the housing and inner surfaces of the plunger to position the iirst spring sections outwardly from the transverse wall. The first yspring sections of the springs each include a contacting iinger and a camming portion. With this arrangement, when the base of a lamp is seated into interengagement with the lampholder, the

camming portions or" the iirst spring sections act upon the contacting ringer thereof and cause it to exert a laterally directed contact pressure upon mating contacts of the lamp. This laterally directed Contact pressure is in a direction transverse to the axis of movement of the plunger and it provides an excellent electrical contact wiping action while at the same time tending to mechanically retain the lamp base in secure interengagernent with the lampholder.

Further aspects oi my invention will become apparent hereinafter, and the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which l regard as my invention. The invention, as to organization and method or" operation, together with further objects and advantages thereof, may best be understood by reference to the following description, when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a compressible lampholder embodying one form of my invention, and one end of a fluorescent lamp in engagement with the lampholder;

FlG. 2 is a sectional View of the lampholder of FIG. l, taken generally along the line 22 of FIG. l;

FIG. 3 is an enlarged fragmentary sectional View of one side of the contact positioning member of the lampholder of FIG. l, showing the arrangement of the contacting spring therein;

FIG. 4 is a View similar to FiG. 2, with part of the contact positioning member shown in full, and the base end of the iluorescent lamp interengaging the lampholder;

FIG. 5 is an enlarged fragmentary sectional View of a second form of contacting spring embodying my invention;

FIG. 6 is a View similar to FIG. 5, showing a lamp base contact interengaged with the contacting spring;

FIG. 7 is an enlarged fragmentary View of a third form of contacting spring embodying my invention;

FIG. 8 is a View similar to FIG. 7, showing a lamp base contact interengaged with the contacting spring;

FIG. 9 is an enlarged fragmentary sectional view of a fourth form of contacting spring embodying my invention; and

FIG. l0 is a View simar to FlG. 9, showing a lamp base contact interengaged with the contacting spring.

Referring to FIG. l of the drawings, in which like numbers denote like parts in all the figures, there is illustrated one end of a conventional type of double-ended iluorescent lamp l which interengages a compressible lampholder 3 constructed in accordance with my invention. The lampholder 3 is suitably secured to a support (not shown) of a lighting fixture. The other and opposite end (not shown) of the lamp 1 interengages a stationary larnpholder (not shown) and the lamp 1 is thus removably arranged in compression between the stationary lampholder and the lampholder 3, in the well known manner.

As shown in FIGS. 1 and 4, the lamp 1 has a tubular glass envelope 5 provided with a base 7 located at the end of the lamp 1 which engages the lampholder 3. The lamp base 7 comprises an annular metal shell 9 and an insulating element 11 secured thereto. The element 11 includes an annular flanged portion 12 which is secured to the shell 9, and an oval shaped embossment 13, part of which is shown in section in FIG. 4. The embossment 13 has a passageway l5 formed therein, and on opposite sides of passageway 15 a pair of lamp contacts 17 are secured to the insulating element 11, one of these lamp contacts 17 being shown in FIG. 4. The lamp contacts 17 thus extend inwardly through passageway 15 into the glass envelope 5, for connection to a suitable electrode (not shown). The outer ends of the lamp contacts 17 are bent over and away from the longitudinal axis of the envelope 5, and then doubled back, as shown in FIG. 4, to form a substantially U-shaped termination. The U-shaped termination of each contact 17, thus includes an inner surface 19 parallel to the axis of the envelope, an outwardly facing transverse surface 2l perpendicular to the axis of the envelope, and end section 23 which is doubled back parallel to surface 19. As shall be further explained hereinafter, the surfaces 19 and 21 are electrically and mechanically interengageable with cooperating contacts of the lampholder 3. The end section 23 of the lamp contact 17 cooperates with the embossment 13 to help clamp the contact 17 in its position on the outer face of the lamp base. As further shown in FIG. 4, the U-shaped terminations of the lamp contacts 17 are recessed inwardly from the outermost face 13a of embossment i3 of the lamp base.

Turning now to an important aspect of the present invention, which concerns an improved compressible lampholder 3 which is efficient in operation and economical in cost, attention is directed to FIG. 2. The compressible lampholder 3 comprises a housing Z5 of suitable insulating material effected by the securement of front and back base members 27 and 29 in cooperative relationship. The front base member 27 faces to the left (viewing FIGS. 1 and 2) and it includes a recessed chamber 31 opening into outer end 33 thereof. Within the chamber 31 there is reciprocably and telescopically arranged a contact positioning plunger 35 which combines with the housing members 27 and 2@ to form an insulative housing for a pair of contact making springs 37 of the lampholder. The structure and arrangement of the springs 37 comprises an important part of my invention, as shall be further understood hereinafter.

For telescopically receiving plunger 35, the chamber 3l includes a generally cylindrical cavity 39 and a pair of diametrically opposed grooves formed in the inner walls thereof. The plunger 35 has a generally cyhndrical external configuration of less diameter than the cylindrical cavity 39 and is provided with diametrically opposed ears 41 which project radially outwardly from the plunger 35 and fit into the aforementioned grooves to guide the reciprocating movement of the plunger in cavity 39.

As shown in FIGS. 2 and 4, the contact making springs 37 are arranged in spaced apart relationship within the overall housing provided by the piunger 35 and housing members 27 and Zt). Fach of the springs V37 is of elongated construction and includes an elongated helical section 43 which forms arsubstantial portion of the spring and extends from the right end 45 (viewing FIG. 2) toward the left end 47 (FIG. 2). On and near the left end 47 of the-springs 37, as best shown in FIG. 3, there is formed an irregularly looped contact making and Wiping section 49.

To preclude any undesirable lateral movement of spring end 45, the helical section 43 has its outer end 45 fitted around suitable terminal members 51., which are supported in the back housing member 29. Thus, more particularly as shown in FIGS. 2 and 4, the inner surface of back member 29 facing plunger 35, has the terminal members 51 mounted thereon. Each of the two terminal members 5l includes an annular boss 53 which is received by the outermost end 45 of the helical section 43 of spring 37 to accurately position the one end of the spring 37 in chamber 31 of the lampholder 3. T he other and inner ends 55 of the helical sections 43 of the springs 37 are arranged in cylindrical recesses 57 formed on the inner end of plunger 35. Ends 55 are seated longitudinally against and engage annular shoulders 59 of their associated plunger recesses 57. Thus, as shown in FIGS. 2 and 4, the helical sections 43 of the contact making springs 37 are arranged in continuous compressionbetween annular shoulders 59 of their associated plunger recesses 57 and the inner surface of housing member 29 to continuously bias the Contact positioning plunger 35 to its outermost position (as shown in FIG. 2).

Turning now to the structure of the contact making and wiping section 49 of each of the contact making springs 37, attention is directed in particular to FIG. 3. As shown therein, the inner end 55 of helical section 43 of each spring 37 is bent over at 6l and connected to an integral supporting leg 63. The leg 63 extends in a direction parallel to the axis of movement of plunger 35. In addition, leg 63 is also preferably disposed in a plane which includes the longitudinal axis of helical section 43,V

and it is connected by a bend 65 to a generally Lshaped contacting portion 67 which is also in the same plane. The L-shaped contacting portion 67 includes a transverse branch 69 which is disposed in generally perpendicular relationship to the axis of movement of plunger 35. The branch 69 is connected by bend 71 to limb 73 to form the remainderV of the L-shaped contacting portion 67. The limb 73 is preferably constructed and arranged in the plunger 37 so that it normally slopes laterally and longit is connected to end portion S1 of the cammingtleg 79 at,

elbow S3. The end portion S1 is preferably disposed at a small angle from the portion 77, such as, for example, by an angle of 15 degrees. Portion 31 of the camming leg 79 is normally arranged in the plunger 35 so that its end da is located on edge 35 of a shoulder S7. The shoulder 87 is formed on the inner side of a plunger slot S9 through which the contact making and operating section 49 is extended (FIG. 3).

portion 67, and this plane also includes the axis kof th helical section 43 of the spring 37.

Turning now to an explanation of the mode of operation of the contact malcng and wiping sections 49 of spring 37, attention is directed to FIGS. 2-4. As shown in FIG. 2, when the lamp base 7 of lamp 1 is disengaged from my compressible lampholder 3,V the helical Vsections 43 of the two springs 37 are arranged in compression f Y between back housing member 29 and'annular shoulders 52 (FIG. 3) of the plunger recesses 57, to resiliently'bias i the contact positioning plunger 35 to its outermost position. The contact making and wiping sections 49 extend Y outwardly through slots 3% formed in recessed transverse The camming leg 79 is f disposed in the same plane as the leg 63 and contacting wall 9i), so that bend 65 and L-shaped contacting section 67 of each contact are disposed in outwardly facing cavity 92. Inner portion 77 of camming leg 79 is disposed in a groove 94. formed in the centrally disposed projecting wall 93, as shown in FIG. 3. When the plunger 35 is in this position, the looped over outermost ends 75 of the contact making and wiping sections 49 diverge outwardly slightly from contiguous surfaces 91 of insulating wall 93 (within grooves 94). In addition, elbows 83 of the V-shaped camming legs 79 engage the surfaces 91, and the extreme end of end portion 31a of each leg 79 is disposed on shoulder S7 of the plunger 35, as shown in full in FIG. 3.

When the lamp base 7 of lamp 1 is then inserted into interengagement with the open mouth of the compressible lampholder 3, as the transverse surfaces 21 of the lamp contacts 17 engage transverse branches 69 (FIG. 3) of the springs 37, the camming leg 79 slides inwardly against the edge 85 of plunger shoulder S7, as indicated by the dotted lines of FIG. 3. As a result of the camming action which is achieved by riding end portion 81 of the cumming leg upon edge 85, the looped over outermost end 75 of each of the springs moves laterally `away from the central insulating wall 93 of the plunger to the position indicated by the dotted lines of FIG. 3. The surface of limb 73 which is closest to the inner surface 19 of the lamp contact 17 thereupon exerts a laterally directing biasing force upon inner surface 19 of the lamp.

it will thus be seen that the engagement of transverse surfaces 21 of the lamp contacts 17 with transverse branches 69 (FIG. 3) of the Contact making and wiping sections 49 causes an ecient camming eifect between carnrning leg 79 of contact section 49 and edge 85 of the plunger, to eliect a lateral wiping action of the limbs 73 into secure electrical engagement with the lamp contacts 17. Such an arrangement provides an excellent electrical connection between the lampholder contact springs 37 and the lamp contacts 17. It will further be understood that the springs 37 not only provide the contact Wiping sections 49 for effective engagement with the lamp contacts 17, but they also include an integral means in the form of helical sections 43 for biasing the plunger 35 to its outermost position. The contact making springs 37 may by way of example be constructed of phosphor bronze spring wire having a diameter in the order of 0.036 inch.

FIGS. and 6 represent a modified form of my invention wherein contact making springs 137 have been empioyed in the plunger 35. Spring 137 is similar to spring 37 except for same variance in the configuration of the portion of the spring 137 which interengages the lamp contact 117. For spring y137 and lamp contact 117, the component parts and sections thereof shown in FIGS. 5 and 6, which have -a structural similarity to their correlative parts of spring 37 and lamp contact 17, respectively, are identified by the same two reference numerals, with the numeral 1 prefixed thereto.

The basic dilerence between spring 137 and spring 37 i5 that, instead of the substantially L-shaped contacting portion 67 of spring 37, -a substantially S-shaped contacting portion 167 has been provided. The contact makin.u and wiping section 149 of spring 137 thus includes `supporting leg 163 which is constructed similarly to leg 63 of Contact Spring 37, and extends outwardly through plunger slot S9. From the upper end of leg 163, viewing PEG. 5, outwardly curved section 165 is turned into a larger inwardly curved section 169. The inwardly curved section 1f? is curved into limb 173 which is shorter than limb 73 of contact spring 37. Looped end 175 has the same general coniiguration as loop 75 of spring 37, and cumming leg 17 9 has the same identical configuration as camming leg 79 of the spring 37.

For an understandinD of the Inode of operation of the Contact spring 137 upon interengagement therewith by lamp contact 117, attention is directed to a comparison between FIGS. 5 and 6. As shown in F15. 5, the helical section 143 of spring 137 is arranged in compression in the lampholder, to bias the plunger 35 in the same manner previously set forth for spring 37. The Contact making and wiping section 149 of spring 137 is disposed in a single plane which includes the axis of helical section 143, and it extends through slot 39 in the recessed transverse wall 90, for engagement with a lamp contact 117 moving in a downward direction into the outwardly facing cavity 92. When the lamp contact 117 is disengaged from the contact spring 137, the looped over outermost end 175 of contact spring 137 diverges outwardly slightly from contiguous surfaces 91 of insulating Wall 93, in the same manner previously set forth for end '75 of the contact springs 37. In addition, elbow 133 of the V-shaped camming legs 179 engage surfaces 91, and the extreme end portion 13M of each leg 179 is disposed on shoulder 87 of plunger 35, as shown in FlG. 5.

With the contact spring 137 in the position shown in FIG. 5, when the lamp contact 117 of a fluorescent lamp base is inserted into interengagement With the open mouth of the plunger 35, the inner surface i119 of the lamp contact 117 iirst impinges upon the curved upper end of limb 173, or upon the right side of the looped end 175. This impingem-ent of inner surface 119 of the lamp contact 117 causes the Contact section 149 to move to the position Where it is shown in FIG, 6. The looped end 175 of the contact section 149 is thus placed in compression between Contact surface 119 and plunger surface 9'1. Since the loop 175 tends to return to its original position, it exerts a lateral lbiasing yforce on surface 119 of the lamp contact. This biasing force is in a direction perpendicular to and outwardly from the axis of helical spring section 143 and it provides an effective lateral wiping action of contact section 149 into secure electrical engagement with lamp contact 117.

'it should further be understood that if the Contact 117 of FIG. 6 is arranged so that transverse surface 121 engages the outwardly curved portion of contact spring 137 before the inner surface 119 of the lamp contact 117 engages the looped outer end thereof, then the same camming action previously described tfor the contact wiping section 49 of contact spring 37 occurs. it will thus be understood that the mode or operation of contact springs 137 is similar to that previously described for the springs 37.

FGS. 7 and 8 represent a modified form of my invention wherein contact making springs 237 have been employed in the plunger 35. Spring 237 is similar in structure and function to spring 137, except that the contact making and wiping section 249 is supported by means of the camming leg 279. Thus, as shown in FlGS. 7 and 8, the leg 263 is disposed on the right side of plunger slot 39, and the camming leg 279 is disposed on the other (i.e., inner) side thereof and secured to the helical section 243. With this contact mrangement, the coaction and cooperation between the contact making and wiping section 2li-9 and lamp Contact 217 is identical to that described above for the contact spring 137.

FIGS. 9 and l0 represent another modilied vform of my invention wherein contact making springs 337 have been employed in the plunger 35. Spring 337 diifers `from the previously discussed springs, in that the contact making and wiping sections 349 have a Z-shaped conguration. Thus, as shown in FIG. 9, supporting leg 363 forms one side of the Z and is parallel to the axis of helical section 3413. The upper end of ieg 363 is bent over at 3642i and then diagonally toward inner surface 911 of the plunger 35 to form an intermediate strut 365. Strut 365 is bent around a curved section 366 and then back upwardly and away from inner surface 91 to form a movable free end 367 of the contact spring 337.

When the lamp contact 317 interengages contact spring 337, as shown in FIG. 10, the free end edge 3674i of end portion 367 exerts a compressive force upon lamp contact portion 319 of the lamp to provide the desired lateral biasing force for wiping. In addition, a sloped surface 8521 is provided on the inner end of cavity 92 to allow the curved section 366 to slide downwardly from the position in FlG. 9 to that of FIG. l0. With such an arrangement an etiective lateral wiping action is achieved for interengagement of the contact spring 337 with lamp contact 317.

lt will now, therefore, be seen that the present invention provides a novel and improved fluorescent lampholder which is efficient in operation, and which due to its relative simplicity may be economically manufactured. it will further he understood that the improved Contact spring arrangements of the present invention perform a plurality of ecient functions in an expeditious manner.

While in accordance with the patent statutes, l have described what at present are considered to be the preferred embodiments of my invention, it will be obvious to those skilled in the art that various changes and modiiications may be made therein without departing from my invention, and I, therefore, aim in the following claims to cover all such equivalent variations as fall Within the true spirit and scope of this invention.

What I claim as new and desire to Patent of the United States is:

l. A fluorescent lampholder comprising an open ended casing, a contact positioning plunger arranged for reciprocation in said casing and substantially closing the open end thereof to form a housing for the larnpholder, said contact positioning plunger having an outer tace adapted to receive a lamp base, a centrally disposed insulative spacing means within said plunger, and a pair of spaced apart contact wiping springs located in said housing and separated by said spacing means, each of said springs including a first resilient section disposed at one of its ends and a second resilient section comprising the remainder thereof, said first resilient sections being exposed Yat said outer face of said plunger `for engaging contacts of said lamp base, said second resilient sections heing arranged in compression between said casing and said lplunger thereby to bias said contact positioning plunger outwardly kfrom said casing and to bias said rst spring sections in the same direction as said plunger, said iirst resilient sections also including a camming portion disposed in engagement with said spacing means, and means including sain cammino portions and said spacing means for moving said first resilient portions laterally to the axis of -reciprocation of said plunger when the contacts of said lamp are seated in said lampholder thereby to exert a laterally directed contact pressure upon the contacts of said lamp,

'2. A fluorescent lampnolder comprising an open ended casing, a Contact positioning plunger arranged for reciprocation in said casing and substantially closing the open end thereof to form a housing for the lampholder, said contact positioning plunger having an outer face adapted to receive a lamp base, inner wall means within said plunger, and at least one contact wiping spring located in said housing, said spring including a first resilient section disposed at one of its ends and a second resilient section comprising the remainder t ereof said rst resilient section being exposed at said outer face of said plunger for engaging a contact of said lamp base, said second resilient section being arranged in compression between said casing and said plunger thereby to bias said contact positioning plunger outwar ly lfrom said casing and to bias said first spring section in the same direction as said plunger, and means including'said first resilient section and said inner wall means of said plunger for moving said hrst resilient section laterally to the axis of reciprocation of said plunger when the contact of said lamp is seated in said lampholder, thereby to exert a laterally directed Contact pressure upon the contacts of said lamp.

3. A lampholder'for receiving the contacts of a recessed double contact lamp, said larpholder comprising secure by Letters walls dening an open-ended housing, a hollow contact positioning member telescopically arranged within said housing, said member having a transverse partition recessed from its outer end and defining with the walls of said member an outwardly opening cavity, and a pair of contact receiving slots extending through said partition, spacing means extending longitudinally between said'slots in said positioning member to form a pair of separated chambers, and a pair of spaced electrical contact making and wiping springs disposed at least partially within said chambers, each of said springs including a first resilient section disposed at one of lits ends and a second resilient section comprising the remainder thereof, the first resilient sections of the springs extending through said slots in said partition and terminating within said cavity, the second resilient sections being arranged in compression between the housing and the respective inner ends of the chambers thereby to bias said first spring sections outwardly through said slots and to bias said contact positioning member outwardly from said housing, said iirst resilient sections each including a camming portion disposed in engagement with said spacing means, and means including said camming portions and said spacing means for moving said rst resilient portions laterally to the axis of reciprocation of said plunger when the contacts of said lamp are seated in said lampholder thereby to exert a laterally directed contact pressure upon the contacts of said lamp.

4. The lampholder or" claim 1 wherein the rst resilient section of each of the contact wiping springs includes a substantially L-shaped contacting portion, a first leg of said contacting portion being disposed transversely to the axis of movement of said plunger and a second leg normally disposed .in generally parallel relationship to the axis of movement of said plunger.

5. The lampholder of claim 4 wherein the second leg of said L-shaped contacting portion forms a side of a doubled back outer end of said first resilient section, said camming portion forming the other side of said doubled back outer end and having the coniiguration of a shallow V, said camming portion of said first resilient section being arranged to coact with a step formed on said centrally disposed spacing means of said plunger for camrning said first resilient sections when the contacts of saidV lamp are seated in said lampholder.

6. T he lampholder of claim 5 wherein'the second resilient sections of the contact wiping springs have a helical configuration with the axis of the helix parallel to the axis of movement of the plunger', and the first resilient sec-l generally S-shaped contacting portion for engaging a mating contact of said lamp.

8'. The lampholder of claim 1 wherein the first resilient sections of each of the contact wiping springs has a generally Z-shaped contiguration, the extremeV end of said first resilient section being exposed by said plunger forV engagement with an associated lamp contact and operable by an associated camming portion to exert a laterally ,dil

erected contact pressure upon said lamp Contact.

9. The lampholder of claim 8 wherein the camming portion includes a curved elbow which coacts with a sloped shoulder of said centrally disposed spacing means.

l0. A fluorescent lampholder comprising an open endedY casing, a contact positioring plunger arranged for re-Y iprocation in said casing and substantially closing the open end thereof to form a housing for the lampholder,Y

said contact positioning plunger having an outer face adapted to receive a lamp base, a centrally disposed insulative spacing means within said plunger, and a. pair of spaced apart Contact wiping springs located in saidV housing and separated by said spacing means, each of said springs including a iirst resilient section disposed at one of its ends and a second resilient section comprising the remainder thereof, said -rst resilient sections being eX- posed at said outer face of said plunger `for engaging contacts of said lamp base, said second resilient sections being arranged in compression between said casing and said plunger thereby to bias said contact positioning plunger outwardly from said casing and to bias said rst spring sections in the same direction as said plunger, and means including said rst resilient sections and said centrally disposed spacing means -for compressing a p01'- tion of said rst resilient sections when the contacts of said lamps are seated in said lampholder thereby to exert a laterally directed contact pressure upon the contacts of said lamp.

References Cited in the file of this patent UNITED STATES PATENTS 2,716,738 Pistey Aug. 30, 1955 2,722,666 Hodgkins Nov. l, 1955 2,977,563 Lennox Mar. 28, 1961 FOREIGN PATENTS 795,439 Great Britain May 21, 1958 

2. A FLUORESCENT LAMPHOLDER COMPRISING AN OPEN ENDED CASING, A CONTACT POSITIONING PLUNGER ARRANGED FOR RECIPROCATION IN SAID CASING AND SUBSTANTIALLY CLOSING THE OPEN END THEREOF TO FORM A HOUSING FOR THE LAMPHOLDER, SAID CONTACT POSITIONING PLUNGER HAVING AN OUTER FACE ADAPTED TO RECEIVE A LAMP BASE, INNER WALL MEANS WITHIN SAID PLUNGER, AND AT LEAST ONE CONTACT WIPING SPRING LOCATED IN SAID HOUSING, SAID SPRING INCLUDING A FIRST RESILIENT SECTION DISPOSED AT ONE OF ITS ENDS AND A SECOND RESILIENT SECTION COMPRISING THE REMAINDER THEREOF, SAID FIRST RESILIENT SECTION BEING EXPOSED AT SAID OUTER FACE OF SAID PLUNGER FOR ENGAGING A CONTACT OF SAID LAMP BASE, SAID SECOND RESILIENT SECTION BEING ARRANGED IN COMPRESSION BETWEEN SAID CASING AND SAID PLUNGER THEREBY TO BIAS SAID CONTACT POSITIONING PLUNGER OUTWARDLY FROM SAID CASING AND TO BIAS SAID FIRST SPRING SECTION IN THE SAME DIRECTION AS SAID PLUNGER, AND MEANS INCLUDING SAID FIRST RESILIENT SECTION AND SAID INNER WALL MEANS OF SAID PLUNGER FOR MOVING SAID FIRST RESILIENT SECTION LATERALLY TO THE AXIS OF RECIPROCATION OF SAID PLUNGER WHEN THE CONTACT OF SAID LAMP IS SEATED IN SAID LAMPHOLDER, THEREBY TO EXERT A LATERALLY DIRECTED CONTACT PRESSURE UPON THE CONTACTS OF SAID LAMP. 